Electronics unit with integrated metallic pattern

ABSTRACT

A non-conductive encapsulation cover is mounted on a support face of a support substrate to delimit, with the support substrate, an internal housing. An integrated circuit chip is mounted to the support substrate within the internal housing. A metal pattern is mounted to an internal wall of the non-conductive encapsulation cover in a position facing the support face. At least two U-shaped metal wires are provided within the internal housing, located to a side of the integrated circuit chip, and fixed at one end to the metallic pattern and at another end to the support face.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.17/878,436, filed Aug. 1, 2022, which is a divisional of U.S.Application for patent Ser. No. 17/165,295, filed Feb. 2, 2021, whichclaims the priority benefit of French Application for Patent No.2001103, filed on Feb. 4, 2020, the contents of which are herebyincorporated by reference in their entireties to the maximum extentallowable by law.

TECHNICAL FIELD

Embodiments and applications relate to microelectronics and, inparticular, to the field of electronics units and particularly that ofelectronics units comprising a non-conductive encapsulation covermounted on a support substrate and incorporating an antenna.

BACKGROUND

A support substrate is typically used for supporting and connecting oneor more electronic integrated circuit chips and possibly components ofthe surface mounted device (SMD) type. A non-conductive encapsulationcover is used, in particular, for enclosing the electronic integratedcircuit chip and other possible components and thus arranging a deviceor unit which is able to be manipulated and is protected from externalconditions.

The mounting of the non-conductive encapsulation cover to the supportsubstrate conventionally comprises arranging a strip of adhesive, forexample on the periphery of the bearing surface of the supportsubstrate, and joining together the cover and the substrate bycontacting the strip of adhesive.

The incorporation of an antenna into the unit is increasingly demandedby users, particularly for future radiofrequency applications, forexample 5G but by no means limited to 5G applications, that require ahigh degree of integration.

Current solutions provide the formation of the antenna on the bearingsurface of the support substrate by depositing a specific metal or evenby soldering the cover to the substrate.

Such solutions lead to an increase in the size of the units and/or to anincrease of the manufacturing costs.

It is thus necessary to propose a different solution for incorporatingan antenna into a unit which does not have a negative impact on thebulkiness of the surface and/or on the manufacturing costs.

SUMMARY

According to one embodiment, it is proposed to use U-shaped metal wires,which makes it possible to connect a metallic pattern arranged on theinternal face of the cover to the bearing surface of the substrate. Thismakes it possible to either: form an antenna and connect it in a simplemanner to a component located on the bearing surface of the substrate;or form an electromagnetic protective shield that can thus be arrangedas close to the component as possible. A plurality of U-shaped metalwires can be arranged, for example, around the electronic integratedcircuit chip so as to form a network that is as dense as possible inorder to ensure good electromagnetic protection.

Furthermore, the formation of said U-shaped metal wires can be carriedout advantageously in the same way as the formation of wire bondingbetween the electronic integrated circuit chip and the substrate, whichdoes not require a different manufacturing process.

According to one aspect, a unit or device is proposed, comprising: asupport substrate having a bearing surface; a non-conductiveencapsulation cover mounted on said bearing surface of the supportsubstrate and delimiting with the support substrate an internal housingof the unit; at least one electronic integrated circuit chip located inthe internal housing and supported by said bearing surface; a metallicpattern arranged at least on an internal wall of the non-conductiveencapsulation cover located opposite the bearing surface; and aplurality of U-shaped metal wires extending into said internal housing,to the side of said at least one electronic integrated circuit chip,being fixed on the one hand to the metallic pattern and on the otherhand to the bearing surface.

The expression “U-shaped” should be interpreted very broadly to includeany curved structure with two branches, even if this structure is notexactly U-shaped.

According to one embodiment, the bend of each U-shaped metal wire can befixed onto the metallic pattern and the two legs of each U-shaped metalwire can be fixed onto the bearing surface.

In one variant, it is possible to fix the two legs of the U-shaped metalwire onto the metallic pattern, the bend of the U-shaped metal wirebeing fixed onto the bearing surface.

The use of U-shaped metal wires is compatible with all methods ofmounting the electronic integrated circuit chip onto the bearingsurface.

Thus, it is of course possible to mount the electronic integratedcircuit chip by means of connecting balls soldered onto the bearingsurface and coated with an underfill material.

That being said, it is also possible to use another conventionalmounting method, which is known per se, of the electronic integratedcircuit chip onto the bearing surface of the substrate comprisingsoldered wire bonding between the metallic pads of said at least oneelectronic integrated circuit chip and metal areas located on thebearing surface of the support substrate.

In this case, the U-shaped metal wires are structurally identical tothese bonding wires which are obtained advantageously by an identicalmethod.

According to one embodiment, the unit comprises an antenna including themetallic pattern and a connector, making it possible to connect saidantenna to at least one component located on said bearing surface, saidconnector including at least two U-shaped metal wires.

These two U-shaped metal wires thus make it possible to connect the twoterminals of the antenna to a component or to a circuit located on thebearing surface of the unit, for example a circuit for adapting theimpedance.

According to another possible embodiment, the unit can include aplurality of U-shaped metal wires arranged at the periphery of theinternal housing and surrounding said at least one electronic integratedcircuit chip.

The unit can thus include an electromagnetic protective shield includingsaid metallic pattern and said U-shaped metal wires arranged at theperiphery of the internal housing.

According to another aspect, a method for forming a unit comprises:providing a support substrate having a bearing surface; mounting atleast one electronic integrated circuit chip on the bearing surface (theterm “mounting” should be interpreted very broadly here, including notonly fixing the electronic integrated circuit chip onto the bearingsurface but also the formation of its connector, for example by means ofconnecting balls coated with an underfill material or even the formationof wire bonding and soldering thereof); fixing a plurality of U-shapedmetal wires onto the bearing surface, projecting to the side of said atleast one electronic integrated circuit chip; providing a non-conductiveencapsulation cover; forming a metallic pattern at least on the internalwall of the cover designed to be opposite the bearing surface aftermounting the cover on the bearing surface; locally forming solderingmeans, for example soft pads of soldering paste, onto said metallicpattern; mounting the non-conductive encapsulation cover onto saidbearing surface of the support substrate such that the projecting endsof the U-shaped metal wires come into contact with the localizedsoldering means; and raising the temperature of the unit, for example byheating in an oven, so as to solder the projecting ends of the U-shapedmetal wires onto the metallic pattern.

According to another aspect, a method for forming a unit comprises:providing a support substrate having a bearing surface; mounting atleast one electronic integrated circuit chip on the bearing surface;locally forming soldering means, for example soft pads of solderingpaste, on said bearing surface, to the side of said at least oneelectronic integrated circuit chip; providing a non-conductiveencapsulation cover; forming a metallic pattern at least on the internalwall of the cover designed to be opposite the bearing surface aftermounting the cover on the bearing surface; fixing a plurality ofprojecting U-shaped metal wires onto the metallic pattern designed toextend to the side of said at least one electronic integrated circuitchip after mounting the cover on the bearing surface; mounting thenon-conductive encapsulation cover onto said bearing surface of thesupport substrate in such a manner that the projecting ends of theU-shaped metal wires come into contact with localized soldering means;and raising the temperature of the unit so as to solder said projectingends of the U-shaped metal wires onto said bearing surface.

In one or other of these other aspects, the projecting ends of theU-shaped metal wires are advantageously the bends of the U-shaped metalwires.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features of the invention are described in thedetailed description of embodiments and applications, which are by nomeans limiting, and the attached drawings in which:

FIG. 1 is schematic diagram of a unit or device;

FIG. 2 is schematic diagram of a unit or device;

FIG. 3 is a plan view;

FIG. 4 shows steps of a method; and

FIG. 5 shows steps of a method.

DETAILED DESCRIPTION

In FIG. 1 , reference numeral 1 denotes a unit or device comprising asupport substrate 10 having a bearing surface 100 and a non-conductiveencapsulation cover 40 mounted on the bearing surface 100 by means of astrip of adhesive 50, having a thickness commonly referred to by aperson skilled in the art as the bond line thickness (BLT).

The adhesive is a known epoxy adhesive, for example.

Typically, the thickness of this strip of adhesive 50 is limited inquantity to maintain a given position of vertical positioning of thecover on the substrate. For example, to maintain a precision of thevertical positioning of more or less 10 micrometers, the thickness ofthe strip of adhesive is capped at 15 micrometers.

The support substrate 10 is designed to support at least one electronicintegrated circuit chip 20 and to establish electrical connectionsbetween the terminals of the electronic integrated circuit chip and theexterior of the unit 1.

The internal wall of the non-conductive encapsulation cover 40 delimitswith the carrier substrate 10 an internal housing (or volume) 400designed to receive the electronic integrated circuit chip 20.

In the example illustrated in FIG. 1 , the electronic integrated circuitchip 20 is electrically connected to metallic areas of the bearingsurface 100 of the support substrate by connecting wires 21.

The non-conductive encapsulation cover 40 also includes, on its internalwall located opposite the bearing surface 100 of the support substrate(i.e., on an underside of the front wall of the cover 40), a metallicpattern 60 which can be, for example, either: a solid metal plate in thecase of an electromagnetic protective shield, or a specific metalpattern in the case of the formation of an antenna.

In this embodiment, U-shaped metal wires 30 are also provided within theinternal housing 400, located to the side of the electronic integratedcircuit chip 20, and extending between the bearing surface 100 of thesupport substrate and the metallic pattern 60.

In this embodiment, the bend of each U-shaped metal wire is located atthe level of the metallic pattern and is fixed to the metallic patternby means of an electroconductive soldering paste 302.

Two legs 300 and 301 of each U-shaped metal wire extend from the bendand are fixed, for example by soldering, onto the metallic areas of thebearing surface 100 of the support substrate.

In the embodiment variant illustrated in FIG. 2 , this time the bends ofthe U-shaped metal wires are fixed onto the bearing surface of thesupport substrate by means of soldering pads 302. Furthermore, the legs300 and 301 of the U-shaped metal wires are soldered onto the metallicpattern 60.

It is possible advantageously, as illustrated very schematically in theplan layout of FIG. 3 , to provide a plurality of U-shaped metal wires30 arranged at the periphery of the internal housing 400 of the unit andtherefore surrounding the electronic integrated circuit chip or chipslocated in the unit as well as all the other possible components.

This is particularly advantageous in the case of an electromagneticshield and makes it possible to obtain a dense peripheral network orcurtain of U-shaped metal wires.

Reference is now made in particular to FIGS. 4 and 5 to illustrate waysof implementing the method of manufacturing the unit.

FIG. 4 refers more particularly to an implementation which makes itpossible to obtain a unit of the type illustrated in FIG. 1 , whereasFIG. 5 refers more particularly to a method of implementation whichmakes it possible to obtain a unit of the type illustrated in FIG. 2 .

In step S40 of FIG. 4 , the support substrate is provided, on which instep S41 the mounting of the electronic integrated circuit chip isperformed, including fixing the electronic integrated circuit chip aswell as forming its electrical connection, for example by means ofconnecting wires 21.

Then, in step S42, the formation and fixing of U-shaped metal wires 30is performed on the metallic areas of the substrate.

The method of forming said wires in a U shape is identical to that offorming the connecting wires 21 of the electronic integrated circuitchip. In particular, use of bonding wire technology and fabricationtechniques may be used for both the connecting wires 21 and U-shapedmetal wires 30.

More precisely, conventionally, a wire is arranged having a ball at itsend which is crushed onto a first metallic area of the substrate.

Then the wire is shaped in order to obtain the U-shape and the end ofthe other branch of the U-shaped metal wire is crushed onto anothermetallic area of the substrate which fixes it and severs the rest of thewire, then forms again a ball which will be used for forming anotherU-shaped metal wire.

Typically, the diameter of said U-shaped metal wires can vary between 20and 25 micrometers.

Therefore, at the end of step S42, U-shaped metal wires are obtainedwhich are fixed onto the bearing surface of the substrate and projectfrom said bearing surface. The height of the wires in the U-shaped metalwire can vary between 500 and 1000 Angstroms.

In this way a very good degree of rigidity is obtained for the U-shapedmetal wires and their flexibility makes it possible for them to easilywithstand dilatation during the increase in temperature of the units.

Steps S43 to S45 are performed parallel to steps S40 and S42.

It should be noted here that, of course, said steps S43, S44 and S45 canbe carried out before steps S40 to S42 or even after or evensimultaneously to steps S40 to S42.

In step S43, the non-conductive encapsulation cover 40 is provided andthe metallic pattern is formed on its internal wall, which is designedto be opposite the bearing surface after mounting the cover on thesupport substrate.

This metallic pattern can be formed or example by vapor phase metaldeposition or by direct laser engraving known by the person skilled inthe art as laser direct structuring (LDS).

Then, in step S45, a localized deposit of a soft soldering paste isperformed onto the metallic pattern, for example a soft paste with abase of tin, silver and copper.

In step S46, the non-conductive encapsulation cover is mounted onto thesupport substrate. During this assembly the ends of the walls of thecover sink into the epoxy adhesive 50.

Likewise, during this assembly, the bends of the U-shaped metal wiresink into the soft pads of soldering paste 302.

Then the unit is heated S47.

During the heating, the adhesive 50 polymerizes, for example at 150° C.,so as to ensure the adhesion of the cover.

Furthermore, the heating also enables the soft soldering paste to beheated to a high enough temperature, for example 260° C., to solder theU-shaped bend to the metallic pattern.

Referring now to FIG. 5 , it is shown that this time the localizeddeposit of soldering paste is performed in step S52 on the bearingsurface of the support after step S50 of providing the support substrateand step S51 of mounting the electronic integrated circuit chip.

With regard to the cover, the latter is provided in step S53 and themetallic pattern is formed in step S54.

Then, the U-shaped metal wires are fixed, for example by soldering, ontothe metallic pattern in step S55.

This time there are U-shaped metal wires projecting from the internalwall of the unit.

And, when mounting the non-conductive encapsulation cover onto thesupport substrate in step S56, the projecting ends of the U-shaped metalwires enter into the pads of soldering paste, which enable saidprojecting ends to be fixed onto the metal areas of the supportsubstrate during the heating S57 of the unit.

1. A method, comprising: mounting at least one electronic integratedcircuit chip on a bearing surface of a support substrate; locallyforming a portion of solder material on the bearing surface; forming ametallic pattern at least on an internal wall of a non-conductiveencapsulation cover; fixing first ends of a plurality of U-shaped metalwires onto the metallic pattern; mounting the non-conductiveencapsulation cover on said bearing surface of the support substratesuch that the internal wall is positioned opposite the bearing surfaceand second ends of the U-shaped metal wires are in contact with thelocally formed portion of solder material; and raising a temperature ofsaid locally formed portion of solder material so as to solder saidsecond ends of the U-shaped metal wires onto the bearing surface.
 2. Themethod according to claim 1, wherein a bend of each U-shaped metal wireprovides said second end that is soldered to the bearing surface andwherein ends of two legs of each U-shaped metal wire extending from thebend provide said first end that is fixed to the metallic pattern. 3.The method according to claim 2, wherein the metallic pattern is anantenna.
 4. The method according to claim 3, wherein the metallicpattern is a portion of an electromagnetic shield.
 5. The methodaccording to claim 1, wherein mounting the non-conductive encapsulationcover comprises attaching the non-conductive encapsulation cover to thebearing surface using an adhesive material, and wherein raising thetemperature of said locally formed portion of solder material comprisesapplying heating to both cure the adhesive material and performsoldering of said second ends of the U-shaped metal wires onto thebearing surface.
 6. The method according to claim 1, wherein forming themetallic pattern comprises performing a vapor phase metal deposition. 7.The method according to claim 1, wherein forming the metallic patterncomprises performing a direct laser engraving.
 8. The method accordingto claim 7, wherein said direct laser engraving comprises laser directstructuring (LDS).
 9. The method according to claim 1, wherein saidlocally formed portion of solder comprises a soft soldering paste. 10.The method according to claim 1, wherein mounting the non-conductiveencapsulation cover comprises: depositing an adhesive material on saidbearing surface of the support substrate; and placing ends of walls ofthe non-conductive encapsulation cover in contact with the adhesivematerial.
 11. The method according to claim 10, wherein mounting thenon-conductive encapsulation cover comprises applying heat to cure saidadhesive material.
 12. The method according to claim 11, whereinapplying heat to cure said adhesive material further heats the locallyformed portion of solder to perform the soldering of said second ends ofthe U-shaped metal wires onto the bearing surface.
 13. The methodaccording to claim 10, wherein said adhesive material is an epoxy. 14.The method according to claim 1, further comprising placing connectingwires extending between metallic pads of said at least one electronicintegrated circuit chip and metallic areas located on the bearingsurface.
 15. The method according to claim 14, wherein the U-shapedmetal wires are structurally identical to the connecting wires.
 16. Themethod according to claim 14, wherein the U-shaped metal wires and theconnecting wires are formed by bonding wires.